Paper-thin graphene electronics move closer to reality

The
performance of future electronic devices using nanotechnologies is set to
improve thanks to a new and better process for synthesizing Hexagonal Boron
Nitride (h-BN), an ultra-thin insulator used with wonder-nanomaterial graphene1.

Graphene is only one or two atoms thick, while also being very strong, and
a heat and electricity conductor. It shows promise in creating everything from paper-thin television screens to bullet proof vests, but needs an insulating layer so that it can be held while electrically charged.

The compound
h-BN is the world’s thinnest insulator and it has an atomically smooth surface
devoid of charged impurities. This surface makes it an ideal material to
support a layer of graphene, which requires an impurity-free and ultra-smooth
interface.

The scientists Vikas Berry (left) and Sanjay BehuraSeveral
techniques have been employed to synthesize thin films of h-BN, but most create
structural defects that in turn degrade graphene performance. Now Sanjay Behura
and Vikas Berry at the University of Illinois in Chicago report a new improved
process for producing the h-BN insulating layer.

Currently, a
h-BN film is produced on top of a metallic layer (like copper, nickel, cobalt
or iron) and then transferred onto silicon-based layers. "These transfer
steps consistently degrade h-BN’s structure via formation of tears, folds,
wrinkles, and adsorption of polymeric or metallic impurities," Behura and
Berry told Nature India.

The
researchers and their colleagues at technology company SunEdison Semiconductor
have leveraged surface chemical interactions of h-BN precursors to form large-area,
thin films of h-BN directly onto silicon-based layers, eliminating the
defect-creating first step.

They also
created large-area ‘heterostructures’, or layered structures, of h-BN with
graphene via an all ‘chemical-vapor-deposition’ approach. The researchers found
this exhibited 3.5-fold enhancement in charge carrier mobility – the speed at
which a charge like electricity moves through the material in a given direction
– compared to graphene on silicon-based
gate dielectric field effect transistor devices.

The application
of these methods could help produce future technologies ranging from nanoscale
electronics to energy conversion devices and optoelectronics, the
researchers say.